Driving device for revolving members



Jan. 4, 1949. P. G. VANN l 2,458,452

DRIVING DEVICE FOR REVOLVING MEMBERS Filed Feb. 18, 1944 Patented Jan. 4, 1949 a ain DRIVING DEVICE FOR REVOLVING MEMBERS Pierre Georges Vanni, Neuchatel, Switzerland Application February 18; 1944, Serial No. 522,989 In Switzerland April 5, 1943 1 Claim. (Cl. 1.0311) It is known that the coefficient of friction between two surfaces which slide one on the'other, and especially for certain appropriate substances, diminishes and becomes constant above certain sliding speeds.

It is desirable, therefore, when determining given torques that have to counterbalance certain efiforts with precision. to utilise the friction of sliding surfaces under the pressure desired. Naturally, the application is made for feeble forces where heating and wear are limited.

The invention relates to a driving-device for a revclvingmember. which is characterised in that it comprises a revolving driving member which continually co-operates with the revolving member, which it drives with sliding action through the medium of friction means, with a torque practically independent of the speed of this driving-member.

By this means, a pump can be driven in which the outflow pressure remains constant, even if the fluid requirement varies.

However, as the outflow pressure does not exclusively depend on the effort required by the fluid, but that there is the interior friction in the pump (dependent on the viscosity and on the cleanliness of the liquid) which may vary, it is necessary to provide in certain cases. besides the torque really effective. the requisite torque to absorb these eiforts due to the friction.

In these conditions. the pressure of the fluid leaving the pump should be so able to act as to regulate the driving torque--i. e., the pressure itself should increase or reduce the adherence of the friction members determining the driving torque. A perfect adjustment of the outflow pressure is thus obtained. This pump, fitted with the necessary appliances, can be made to give delivery readings.

In the particular case in which the pump is intended to furnish very exact measures, its function can simply be reduced to controlling the passage of the liquid. In this particular case, the liquid would be brought to the pump at the desired pressure and the pump would simply be driven so as to neutralise the effect of all the interior friction, in such a way that it creates no obstacle to the passage of the liquid and that the pressure is equal both at the intake and at the outflow.

The device to which the invention relates can serve still other ends.

The utilisation of the friction as a means of determining permanent torques independent of the number of driving revolutions is illustrated in the annexeddrawing, which shows, as examples, two forms of execution of the device to which the invention relates:

Figure 1 is a diagrammatic View in partial section of the first form of execution, which includes a gear-pump;

Figure 2 is a front view with a partial section of the device according to Figure 1;

Figure 3 is a similar view to Figure 1, corresponding to a second form of execution;-

Figure 4 is a similar view to Figure 2 relating to this second form of execution.

The device shown comprises a motor 1, the shaft 2 of which drives. by means of a coupling 3, a sliding shaft 4, integral with a plate 5 provided with a friction member 6. bearing, as will be seen later. against a disk I, itself integral with a shaft 8, which is the shaft of a gear-pump 9.

The friction member 6 is pressed against the disk l by a lever is, pulled by a draw-spring H, the tension of which is adjustable by means of a screw 12. Another lever l3 also acts on the lever it; the lever i3 is subject, on the one hand, to the action of a draw spring i l, the tension of which is adjusta le by means of a screw l5. and. on the other hand. to the action of a rod l5, integral with a piston i'l, fixed to a diaphragm is forming one side of a chamber I9. into which the pump 9 discharges. It is seen that, according to Figure 1, when the pressure of the fluid flowing from the pump 9 increases. the rod it acts on the lever It! in the contrary direction to the spring 14. The friction member 6 is pressed against the disk I by a force which depends on the adjustment of the tension of the spring ii, on the adjustment of the tension of the spring i4 and on the pressure of the outflow from the pump 9. The adjustment is determined so that the pressure of the member 5 against the disk I varies automatically. in such a way that the pressure of the fluid in th chamber l9 remains equal at a constant value fixed in advance. The shaft 8 turns a shaft 29 through the medium of two bevel teethed wheels 2|, 22. This shaft 2!! operates in its turn a motometer 23 anda tachometer 3 24 ghrough the medium of two bevel pinions Z5, 6.

The fluid is discharged by the pump into the chamber l 9, from which it enters a pipe controlled by a tap not shown. This tap being shut and the motor I revolving, if the gear-pump is of an appropriate type, watertightness being ensured, this pump can hardly revolve or will revolve only very slowly. Under these conditions, besides dischar ing the fluid, the pump can further, by the number of its revolutions, which corresponds exactly to the discharge, give either the readingof the instantaneous idischarge or the indication ofthe quantity discharge at the end of a certain lapse of time, respectively by means of the tachometer 24 and the motometer 23 graduated directly in fluid quantities. As soon as the aforementioned tap is opened, the fluid begins to flow under the pressure determined by theadjustment, asaindicated above. In order that the functioning of the device be correct, the=frictionmember "6 must act constantlyi. e., the maximum discharge at the tap must never allow the :disk 7 to reach the number ofkrevolutions of the friction member -.6, so that the surfaces .co-operating i by friction should keep the vefiective sliding for formingthe exact and necessary balance to pro wide-the fiuid:at the desired pressure, whether sfiowingior not.

.However, it has .been seen that the interior friction .of the pump exacts ,a variable torque, which has to be added to thatnecessary fordeitermining the pressure. The spring l4 adds its effortto that of the spring ill, but this ,efiort, as has been seen, is counteracted ,by .the action due .to the pressure in the chamber [9. The piston H, which issubject to .this pressure, acts intth-e direction allowing the :desiredcorrection, for, when .thepressure decreases, the spring l4 determines-a greater torque on the shaft 8 and, when this pressure increases, areduction of the torque. .Thusagood stabilisation of .the outflow ,pressure .in His obtained,. evenif the torques required .by the :pumpvaryfrom onemoment to :another. .It understood that,.-as a-variant, a

single lever can b-e substituted for the doublelever arrangement IIl--l 3.

:In the secondform. of. execution, amotor (not shownldrives a ,shaft.'2'l,.-.which in its .turn drives .'-a first gear-pumplfl :which revolves regularly.

This. shaft .21 .operatesalso regularly a shaft.29 through the intermediary of gears .30, 3!, .32. This shaft .29, integral .with .a diski33,,.bearing friction .member .34, v.is ,pressed, as rwillibe seen farther on, .against a disk 35, integral with a shaft-3B, serving vto;drive asecondgear-pumpfi'l. The-shaft :36 operates as wella imotometer and .a tachometer 39, ..through themedium of .bevel teethedwheels -Ml, 41,.of. a shaft .42 and a second pair of bevel wheels 43, .44. The ,pump 28 .dis-

1 charges into a chamber 45, into whichthe .in-

take of the pumps! opens. This pumpjl dis- .piston 50,.fixed toa' diaphragm .5! forming ,one side of==a chamber 52 in communication, through ar pipe 53,- with-the chamber 45. The axial move- :ments of .the rod .49 are transmitted .to. a fork. I otla lever.55 actingontliev disk,33.

I'he'pump .28 sucks the liquid from a, reservoir :56 and discharges it into-thechamber 45. The -.pump:- 28,- of greaterdimensions. than -the ,pump e31,wdischarg-es more than. the. latter ;1 so, acertain quantity of liquid escapes through a valve 51,

which is operated by a spring 58 under tension of a screw-plug 59.

The liquid that has thus passed through the valve 5? returns to the reservoir 56 through a pipe 60. Because of the movements to which the reservoir 56 might be subjected when it is mounted on a lorry or an aeroplane, the pump 28 may draw air with the liquid into the chamber 45. Due to the arrangement that has just been described and to the bafiie fit, this air will escape through the valve 57 and hardly anything but liquid can go through the pump 3'1. In adjusting the tension of the spring 58, the value of the pressure in the chamber 45 can be fixed at willri.:-e., the intake pressure of the pump The pump 31, as has already been seen. opposes scarcely any obstacle to the passage of the liquid. With this object, the pistons 48 and 50 act so asto give the desired drive to this pump. In-

deed, as soon as the pressure in the chamber 66 decreases, the piston 48 moves under the influence of-the higher pressure prevailing in the chamber 52 and, in acting on the lever 55, occasions a suitable driving of the pump 31, which thuspresents no difficulty to the passage of the liquid. .If the piston 48 presents a smaller surface than that of the piston5il, the balance of the system will occur for a value of the outflow pressure of the pump 3'! surpassing by a quantity .determined in advance the intake pressure of this pump. On the other hand, if the sections areequaland suitably chosen so that they give an .adequate push to the friction member 34 against .the disk 35, the smallest variation of pressure between the intake and the outflow of ,the .pump l-31 causes an appropriate variation of .the torque transmitted to the shaft 36i. e., of ..the.d1'ive of the pump 31 in such a way that thelatter-thus presents no diiiiculty to the pas- .sage of the liquid. In these conditions, even if .the ,pump ,is not perfectly watertight. the jump .111 .pressurebetween the intake and the outflow of the pump 37 being practically nil, leaks are so .restrictedthat they are negligible.

It is seen from whatprecedes that the second form of execution described allows of measuring the..discharges .with nice precision. The pump 3-'! has, ;-in.this case,-a strict function of control; -the shaft .36, which drives it, operates also the .motometer 38-and the tachometer 39, which can the graduated respectively in quantities of fluid sand. in delivery ,of the latter.

Inthe two forms of execution described above, the utilisation is seen of a friction which is in- .tended 1-130 create a torque capable of establish- -of apump, comprising a revolving member driving thepump, the outflow pressure of which is atozbe regulated, asecond pump, a revolving driv- -.-ing member rwhich continually cooperates with the first-mentioned revolving member, friction .means between the revolving members for trans- .mitting a torque practically independent of the speed of the revolving driving member, and means wherein theoutfiow pressure of the pumps .controlthe adjustment of the friction means, one

of said pumps being regularly driven and feeds the other which is driven by the revolving member, .the friction .means being operated by a ,memberplacedunder the dependence of the in- .take pressure ,ofthe second pump and by a member placed under the dependence of theoutflow pressure of this same pump whereby the ea en:

1,270,794 Lawson et a1 July 2, 1918 Name Date Pardee May 5, 1925 Mayo Aug. 17, 1937 Horton Sept. 21, 1937 Rosenberger Nov. 7, 1939 Eddins Nov. 5, 1940 FOREIGN PATENTS Country Date Great Britain 1938 

